Does the myocardial performance index affect pulmonary artery pressure in patients with mitral stenosis? A tissue Doppler imaging study

Background: The relation between systolic pulmonary artery pressure (PAP) and mitral stenosis (MS) has been poorly understood. Although the mitral valve area (MVA) is an important factor affecting the PAP, there is a wide spectrum of the PAP in patients with MS despite a similar MVA. So, we analyzed whether the left and right ventricular myocardial performance index (MPI) correlated with the PAP. Methods: Two-dimensional Doppler echocardiography was performed in 46 patients with MS. The left atrial diameter, mean mitral gradient, and MVA were measured. The PAP was derived from the tricuspid regurgitant jet velocity. The ejection time (ET), isovolumetric relaxation time (IRT), and contraction time (ICT) were measured on annulus of interventricular septum, lateral, inferior and anterior wall of left ventricle, and right ventricle free wall from apical two- and four-chamber views in patients with MS and 40 age-matched healthy patients by tissue Doppler imaging (TDI). Then the MPI was calculated as (IRT + ICT) / ET for both left and right ventricle. The correlation of PAP with MVA, mean mitral gradient, left atrial diameter, and left and right ventricular MPI was evaluated. Results: MVA and PAP were measured as 1.57 ± 0.39 cm2 (0.8-2.5 cm2) and 42 ± 16 mmHg, respectively. It was determined that the MPI increased in patients with MS (0.59 ± 0.1 vs 0.48 ± 0.07, P < 0.001). It was also demonstrated that the MVA, left atrial diameter, mean diastolic gradient, and left ventricular MPI were correlated with PAP (r = -0.39 [P = 0.007], r = 0.43 [P = 0.003], r = 0.58 [P < 0.001], and r = 0.65 [P < 0.001], respectively). In multivariate analysis, although the PAP correlated with mean diastolic gradient and MPI (r = 0.39 [P = 0.013], and r = 0.48 [P < 0.001]), it did not correlate with left atrial diameter and MVA. The PAP also correlated with right ventricular MPI (r = 0.63 [P < 0.001]). Conclusion: This study demonstrates that the left ventricular MPI obtained by TDI is an important marker of PAP, and right ventricular MPI correlates with the PAP in patients with MS.